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Chen C, Zhou J, Yu H, Pan X, Tian H. Impact of kdcA, pdhD, and codY gene regulation in Lactococcus lactis 408 on 3-methylbutanal formation during cheddar cheese ripening. Food Microbiol 2025; 130:104768. [PMID: 40210397 DOI: 10.1016/j.fm.2025.104768] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2024] [Revised: 02/21/2025] [Accepted: 03/06/2025] [Indexed: 04/12/2025]
Abstract
3-Methylbutanal, a key volatile compound contributing to the nutty flavor of cheese, was primarily produced through the microbial catabolism of leucine. This study focused on the metabolic pathway of 3-methylbutanal at the genetic level during the ripening of Cheddar cheese. The influence of key genes (kdcA, pdhD, and codY) in Lactococcus lactis 408, a specifically selected adjunct culture, on the production of 3-methylbutanal was evaluated. Over a 14-day ripening period, a minor difference in leucine production was observed among different samples with adjunct culture, while alterations in the genes kdcA and pdhD, which were overexpressed in the strain, led to a decreased concentration of α-ketoisocaproate. Utilizing headspace solid-phase microextraction coupled with gas chromatography-flame ionization detection, a reduction was observed in 3-methylbutanal levels as ripening progressed. However, cheese fermented with the codY knockout strain displayed the highest level of 3-methylbutanal at both 0.5-day and 28-day ripening milestones. Further analysis using an Ag/AgCl electrode to assess the redox environment revealed that the higher redox potential in the codY knockout strain was instrumental in retaining elevated levels of 3-methylbutanal. These findings underscored the critical role of genetic factors in the flavor development of cheese and offered promising targets for enhancing flavor profiles in dairy products through biotechnological interventions.
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Affiliation(s)
- Chen Chen
- School of Perfume and Aroma Technology, Shanghai Institute of Technology, Shanghai, 201418, People's Republic of China.
| | - Junnan Zhou
- School of Perfume and Aroma Technology, Shanghai Institute of Technology, Shanghai, 201418, People's Republic of China.
| | - Haiyan Yu
- School of Perfume and Aroma Technology, Shanghai Institute of Technology, Shanghai, 201418, People's Republic of China.
| | - Xin Pan
- School of Perfume and Aroma Technology, Shanghai Institute of Technology, Shanghai, 201418, People's Republic of China.
| | - Huaixiang Tian
- School of Perfume and Aroma Technology, Shanghai Institute of Technology, Shanghai, 201418, People's Republic of China.
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2
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Jourdain L, Gu W. Designing synthetic microbial communities for enhanced anaerobic waste treatment. Appl Environ Microbiol 2025:e0040425. [PMID: 40377302 DOI: 10.1128/aem.00404-25] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/18/2025] Open
Abstract
Synthetic microbial communities (SynComs) are powerful tools for investigating microbial interactions and community assembly by focusing on minimal yet functionally representative members. Here, we will highlight key principles for designing SynComs, specifically emphasizing the anaerobic digestion (AD) microbiome for waste treatment and upcycling. The AD process has traditionally been used to reduce organic waste volume while producing biogas as a renewable energy source. Its microbiome features well-defined trophic layers and metabolic groups. There has been growing interest in repurposing the AD process to produce value-added products and chemical precursors, contributing to sustainable waste management and the goals of a circular economy. Optimizing the AD process requires a better understanding of microbial interactions and the influence of both biotic and abiotic parameters, where SynComs offer great promise. Focusing on AD microbiomes, we review the principles of SynComs' design, including keystone taxa and function, cross-feeding interactions, and metabolic redundancy, as well as how modeling approaches could guide SynComs design. Furthermore, we address practical considerations for working with AD SynComs and examine constructed SynComs designed for anaerobic waste digestion. Finally, we discuss the challenges associated with designing and applying SynComs to enhance our understanding of the AD process. This review aims to explore the use of synthetic communities in studying anaerobic digestion and highlights their potential for developing innovative biotechnological processes.
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Affiliation(s)
- Lisa Jourdain
- MICROBE laboratory, Institute of Environmental Engineering, School of Architecture, Civil and Environmental Engineering, Swiss Federal Institute of Technology, Lausanne, Switzerland
| | - Wenyu Gu
- MICROBE laboratory, Institute of Environmental Engineering, School of Architecture, Civil and Environmental Engineering, Swiss Federal Institute of Technology, Lausanne, Switzerland
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3
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Yao H, Romans-Casas M, Vassilev I, Rinta-Kanto JM, Puig S, Rissanen AJ, Kokko M. Selective butyrate production from CO 2 and methanol in microbial electrosynthesis - influence of pH. Bioelectrochemistry 2025; 165:109000. [PMID: 40345059 DOI: 10.1016/j.bioelechem.2025.109000] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2025] [Revised: 04/29/2025] [Accepted: 05/05/2025] [Indexed: 05/11/2025]
Abstract
Methanol assisted microbial electrosynthesis (MES) enables butyrate production from carbon dioxide and methanol using external electricity. However, the effects of operational parameters on butyrate formation remain unclear. By running three flat plate MES reactors with fed-batch mode at three controlled pH values (5.5, 6 and 7), the present study investigated the influence of pH on methanol assisted MES by comparing the process performance, microbial community structure, and genetic potential. The highest butyrate selectivity (87 % on carbon basis) and the highest butyrate production rate of 0.3 g L-1 d-1 were obtained at pH 6. At pH 7, a comparable butyrate production rate was achieved, yet with a lower selectivity (70 %) accompanied with acetate production. Butyrate production rate was considerably hindered at pH 5.5, reaching 0.1 g L-1 d-1, while the selectivity reached was up to 81 %. Methanol and CO2 consumption increased with pH, along with more negative cathodic potential and more negative redox potential. Furthermore, pH affected the thermodynamical feasibility of involved reactions. The results of metagenomic analyses suggest that Eubacterium callanderi dominated the microbial communities at all pH values, which was responsible for methanol and CO2 assimilation via the Wood-Ljungdahl pathway and was likely the main butyrate producer via the reverse β-oxidation pathway.
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Affiliation(s)
- Hui Yao
- Faculty of Engineering and Natural Sciences, Tampere University, Korkeakoulunkatu 8, 33720 Tampere, Finland
| | - Meritxell Romans-Casas
- LEQUiA, Institute of the Environment, University of Girona, Campus Montilivi, C/Maria Aurèlia Capmany, 69, Girona E-17003, Spain
| | - Igor Vassilev
- Faculty of Engineering and Natural Sciences, Tampere University, Korkeakoulunkatu 8, 33720 Tampere, Finland
| | - Johanna M Rinta-Kanto
- Faculty of Engineering and Natural Sciences, Tampere University, Korkeakoulunkatu 8, 33720 Tampere, Finland
| | - Sebastià Puig
- LEQUiA, Institute of the Environment, University of Girona, Campus Montilivi, C/Maria Aurèlia Capmany, 69, Girona E-17003, Spain
| | - Antti J Rissanen
- Faculty of Engineering and Natural Sciences, Tampere University, Korkeakoulunkatu 8, 33720 Tampere, Finland
| | - Marika Kokko
- Faculty of Engineering and Natural Sciences, Tampere University, Korkeakoulunkatu 8, 33720 Tampere, Finland.
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4
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Guan Q, Qu Y, Zhai Y, Shi W, Zhao M, Huang Z, Ruan W. Enhancement of methane production in anaerobic digestion of high salinity organic wastewater: The synergistic effect of nano-magnetite and potassium ions. CHEMOSPHERE 2023; 318:137974. [PMID: 36708783 DOI: 10.1016/j.chemosphere.2023.137974] [Citation(s) in RCA: 12] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/16/2022] [Revised: 01/12/2023] [Accepted: 01/25/2023] [Indexed: 06/18/2023]
Abstract
During high salinity organic wastewater (HSOW) anaerobic digestion treatment, the process of methanogenesis can be severely inhibited in the high salinity environment, and the accumulation of volatile organic acids (VFAs) leads to failure of the anaerobic reaction. In this study, nano-magnetite and KCl were adopted to alleviate the inhibitory effect of high salinity and enhance the HSOW anaerobic digestion performance. The result showed that, under the optimal dosage of 200 mg/L, nano-magnetite addition promoted the anaerobic digestion performance, and the methane production increased by 11.06%. When KCl was added with a dosage of 0.174%, the methane production increased by 98.37%. The simultaneous addition of nano-magnetite (200 mg/L) and KCl showed a synergistic effect on enhancing HSOW anaerobic digestion performance, and the methane production increased by 124.85%. The addition of nano-magnetite and KCl promoted the conversion of VFAs, especially accelerated the degradation of propionic acid and butyric acid, also it promoted the activity of acetate kinase, dehydrogenase and F420, and thereby enhanced the methanogenesis process. This study could provide a new method for enhancing the anaerobic digestion of HSOW.
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Affiliation(s)
- Qiuyue Guan
- School of Environment and Civil Engineering, Jiangnan University, Wuxi, 214122, China; Jiangsu Engineering Laboratory for Biomass Energy and Carbon Reduction Technology, Jiangnan University, Wuxi, 214122, China; Jiangsu Key Laboratory of Anaerobic Biotechnology, Jiangnan University, Wuxi, 214122, China
| | - Yunhe Qu
- School of Environment and Civil Engineering, Jiangnan University, Wuxi, 214122, China; Jiangsu Engineering Laboratory for Biomass Energy and Carbon Reduction Technology, Jiangnan University, Wuxi, 214122, China; Jiangsu Key Laboratory of Anaerobic Biotechnology, Jiangnan University, Wuxi, 214122, China
| | - Yujia Zhai
- School of Environment and Civil Engineering, Jiangnan University, Wuxi, 214122, China; Jiangsu Engineering Laboratory for Biomass Energy and Carbon Reduction Technology, Jiangnan University, Wuxi, 214122, China; Jiangsu Key Laboratory of Anaerobic Biotechnology, Jiangnan University, Wuxi, 214122, China
| | - Wansheng Shi
- School of Environment and Civil Engineering, Jiangnan University, Wuxi, 214122, China; Jiangsu Engineering Laboratory for Biomass Energy and Carbon Reduction Technology, Jiangnan University, Wuxi, 214122, China; Jiangsu Key Laboratory of Anaerobic Biotechnology, Jiangnan University, Wuxi, 214122, China.
| | - Mingxing Zhao
- School of Environment and Civil Engineering, Jiangnan University, Wuxi, 214122, China; Jiangsu Engineering Laboratory for Biomass Energy and Carbon Reduction Technology, Jiangnan University, Wuxi, 214122, China; Jiangsu Key Laboratory of Anaerobic Biotechnology, Jiangnan University, Wuxi, 214122, China
| | - Zhenxing Huang
- School of Environment and Civil Engineering, Jiangnan University, Wuxi, 214122, China; Jiangsu Engineering Laboratory for Biomass Energy and Carbon Reduction Technology, Jiangnan University, Wuxi, 214122, China; Jiangsu Key Laboratory of Anaerobic Biotechnology, Jiangnan University, Wuxi, 214122, China
| | - Wenquan Ruan
- School of Environment and Civil Engineering, Jiangnan University, Wuxi, 214122, China; Jiangsu Engineering Laboratory for Biomass Energy and Carbon Reduction Technology, Jiangnan University, Wuxi, 214122, China; Jiangsu Key Laboratory of Anaerobic Biotechnology, Jiangnan University, Wuxi, 214122, China
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Bioinformatics and metabolic flux analysis highlight a new mechanism involved in lactate oxidation in Clostridium tyrobutyricum. INTERNATIONAL MICROBIOLOGY : THE OFFICIAL JOURNAL OF THE SPANISH SOCIETY FOR MICROBIOLOGY 2023:10.1007/s10123-022-00316-y. [PMID: 36609955 PMCID: PMC10397141 DOI: 10.1007/s10123-022-00316-y] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/03/2022] [Revised: 12/04/2022] [Accepted: 12/20/2022] [Indexed: 01/09/2023]
Abstract
Climate change and environmental issues compel us to find alternatives to the production of molecules of interest from petrochemistry. This study aims at understanding the production of butyrate, hydrogen, and CO2 from the oxidation of lactate with acetate in Clostridium tyrobutyricum and thus proposes an alternative carbon source to glucose. This specie is known to produce more butyrate than the other butyrate-producing clostridia species due to a lack of solvent genesis phase. The recent discoveries on flavin-based electron bifurcation and confurcation mechanism as a mode of energy conservation led us to suggest a new metabolic scheme for the formation of butyrate from lactate-acetate co-metabolism. While searching for genes encoding for EtfAB complexes and neighboring genes in the genome of C. tyrobutyricum, we identified a cluster of genes involved in butyrate formation and another cluster involved in lactate oxidation homologous to Acetobacterium woodii. A phylogenetic approach encompassing other butyrate-producing and/or lactate-oxidizing species based on EtfAB complexes confirmed these results. A metabolic scheme on the production of butyrate, hydrogen, and CO2 from the lactate-acetate co-metabolism in C. tyrobutyricum was constructed and then confirmed with data of steady-state continuous culture. This in silico metabolic carbon flux analysis model showed the coherence of the scheme from the carbon recovery, the cofactor ratio, and the ATP yield. This study improves our understanding of the lactate oxidation metabolic pathways and the role of acetate and intracellular redox balance, and paves the way for the production of molecules of interest as butyrate and hydrogen with C. tyrobutyricum.
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6
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Zhang B, Peng C, Lu J, Hu X, Ren L. Enhancing menaquinone-7 biosynthesis by adaptive evolution of Bacillus natto through chemical modulator. BIORESOUR BIOPROCESS 2022; 9:120. [PMID: 38647796 PMCID: PMC10992315 DOI: 10.1186/s40643-022-00609-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2022] [Accepted: 11/01/2022] [Indexed: 11/24/2022] Open
Abstract
Menaquinone-7 (MK-7) is a kind of vitamin K2 playing an important role in the treatment and prevention of cardiovascular disease, osteoporosis and arterial calcification. The purpose of this study is to establish an adaptive evolution strategy based on a chemical modulator to improve MK-7 biosynthesis in Bacillus natto. The inhibitor of 5-enolpyruvylshikimate-3-phosphate synthase (EPSP synthase), glyphosate, was chosen as the chemical modulator to perform the experiments. The final strain ALE-25-40, which was obtained after 40 cycles in 25 mmol/L glyphosate, showed a maximal MK-7 titer of 62 mg/L and MK-7 productivity of 0.42 mg/(L h), representing 2.5 and 3 times the original strain, respectively. Moreover, ALE-25-40 generated fewer spores and showed a higher NADH and redox potential. Furthermore, the mechanism related to the improved performance of ALE-25-40 was investigated by comparative transcriptomics analysis. Genes related to the sporation formation were down-regulated. In addition, several genes related to NADH formation were also up-regulated. This strategy proposed here may provide a new and alternative directive for the industrial production of vitamin K2.
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Affiliation(s)
- Bei Zhang
- College of Biotechnology and Pharmaceutical Engineering, Nanjing Tech University, No. 30 South Puzhu Road, Nanjing, 211816, People's Republic of China
| | - Cheng Peng
- College of Biotechnology and Pharmaceutical Engineering, Nanjing Tech University, No. 30 South Puzhu Road, Nanjing, 211816, People's Republic of China
| | - Jianyao Lu
- College of Biotechnology and Pharmaceutical Engineering, Nanjing Tech University, No. 30 South Puzhu Road, Nanjing, 211816, People's Republic of China
| | - Xuechao Hu
- College of Biotechnology and Pharmaceutical Engineering, Nanjing Tech University, No. 30 South Puzhu Road, Nanjing, 211816, People's Republic of China
- Shanghai JanStar Technology Development Co., Ltd., No. 1288, Huateng Road, Shanghai, 201700, China
| | - Lujing Ren
- College of Biotechnology and Pharmaceutical Engineering, Nanjing Tech University, No. 30 South Puzhu Road, Nanjing, 211816, People's Republic of China.
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Lu P, Wu Y, Bai R, Jiang K, Xu F, Zhao H. Integrated strategy of CRISPR-Cas9 gene editing and small RNA RhyB regulation in Enterobacter aerogenes: A novel protocol for improving biohydrogen production. BIOTECHNOLOGY NOTES (AMSTERDAM, NETHERLANDS) 2022; 3:79-87. [PMID: 39416448 PMCID: PMC11446347 DOI: 10.1016/j.biotno.2022.10.002] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/29/2022] [Revised: 10/24/2022] [Accepted: 10/30/2022] [Indexed: 10/19/2024]
Abstract
Dark fermentation is considered as one of the most practical biological hydrogen production methods. However, current productivity and yield are still not economically viable for industrial applications. This biological process must be improved through multiple strategies, of which screening for more effective microbial strains is an important aspect. Here, based on the hydrogen production pathway of E. aerogenes, we describe three strategies to improve hydrogen production by effectively regulating the anaerobic metabolism of E. aerogenes through genetic modification. This protocol describes in detail how to obtain NADH dehydrogenase-damaged mutants and overexpress Nad synthase genes using the CRISPR-Cas9 gene editing system. In addition, the overexpression of small RNA RyhB was achieved and verified by Northern Blot. This protocol is of great significance for the study of genetic engineering operation in E. aerogenes and other bacteria, and also provides theoretical guidance and technical support for the study of E. aerogenes biological hydrogen production.
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Affiliation(s)
- Ping Lu
- Zhejiang Province Key Laboratory of Plant Secondary Metabolism and Regulation, College of Life Sciences and Medicine, Zhejiang Sci-Tech University, Hangzhou, 310018, China
| | - Yan Wu
- Zhejiang Province Key Laboratory of Plant Secondary Metabolism and Regulation, College of Life Sciences and Medicine, Zhejiang Sci-Tech University, Hangzhou, 310018, China
| | - Ruoxuan Bai
- Zhejiang Province Key Laboratory of Plant Secondary Metabolism and Regulation, College of Life Sciences and Medicine, Zhejiang Sci-Tech University, Hangzhou, 310018, China
| | - Ke Jiang
- Zhejiang Province Key Laboratory of Plant Secondary Metabolism and Regulation, College of Life Sciences and Medicine, Zhejiang Sci-Tech University, Hangzhou, 310018, China
| | - Fangxu Xu
- Liaoning Province Key Laboratory of Cordyceps Militaris with Functional Value, Experimental Teaching Center, Shenyang Normal University, Shenyang, 110034, China
| | - Hongxin Zhao
- Zhejiang Province Key Laboratory of Plant Secondary Metabolism and Regulation, College of Life Sciences and Medicine, Zhejiang Sci-Tech University, Hangzhou, 310018, China
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8
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Sezer YÇ, Bulut M, Boran G, Alwazeer D. The effects of hydrogen incorporation in modified atmosphere packaging on the formation of biogenic amines in cold stored rainbow trout and horse mackerel. J Food Compost Anal 2022. [DOI: 10.1016/j.jfca.2022.104688] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
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9
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Arbter P, Widderich N, Utesch T, Hong Y, Zeng AP. Control of redox potential in a novel continuous bioelectrochemical system led to remarkable metabolic and energetic responses of Clostridium pasteurianum grown on glycerol. Microb Cell Fact 2022; 21:178. [PMID: 36050762 PMCID: PMC9434860 DOI: 10.1186/s12934-022-01902-5] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2022] [Accepted: 08/11/2022] [Indexed: 11/25/2022] Open
Abstract
BACKGROUND Electro-fermentation (EF) is an emerging tool for bioprocess intensification. Benefits are especially expected for bioprocesses in which the cells are enabled to exchange electrons with electrode surfaces directly. It has also been demonstrated that the use of electrical energy in BES can increase bioprocess performance by indirect secondary effects. In this case, the electricity is used to alter process parameters and indirectly activate desired pathways. In many bioprocesses, oxidation-reduction potential (ORP) is a crucial process parameter. While C. pasteurianum fermentation of glycerol has been shown to be significantly influenced electrochemically, the underlying mechanisms are not clear. To this end, we developed a system for the electrochemical control of ORP in continuous culture to quantitatively study the effects of ORP alteration on C. pasteurianum by metabolic flux analysis (MFA), targeted metabolomics, sensitivity and regulation analysis. RESULTS In the ORP range of -462 mV to -250 mV, the developed algorithm enabled a stable anodic electrochemical control of ORP at desired set-points and a fixed dilution rate of 0.1 h-1. An overall increase of 57% in the molar yield for 1,3-propanediol was observed by an ORP increase from -462 to -250 mV. MFA suggests that C. pasteurianum possesses and uses cellular energy generation mechanisms in addition to substrate-level phosphorylation. The sensitivity analysis showed that ORP exerted its strongest impact on the reaction of pyruvate-ferredoxin-oxidoreductase. The regulation analysis revealed that this influence is mainly of a direct nature. Hence, the observed metabolic shifts are primarily caused by direct inhibition of the enzyme upon electrochemical production of oxygen. A similar effect was observed for the enzyme pyruvate-formate-lyase at elevated ORP levels. CONCLUSIONS The results show that electrochemical ORP alteration is a suitable tool to steer the metabolism of C. pasteurianum and increase product yield for 1,3-propanediol in continuous culture. The approach might also be useful for application with further anaerobic or anoxic bioprocesses. However, to maximize the technique's efficiency, it is essential to understand the chemistry behind the ORP change and how the microbial system responds to it by transmitted or direct effects.
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Affiliation(s)
- Philipp Arbter
- Institute of Bioprocess and Biosystems Engineering, Hamburg University of Technology, Denickestraße 15, 21073, Hamburg, Germany
| | - Niklas Widderich
- Institute of Bioprocess and Biosystems Engineering, Hamburg University of Technology, Denickestraße 15, 21073, Hamburg, Germany
| | - Tyll Utesch
- Institute of Bioprocess and Biosystems Engineering, Hamburg University of Technology, Denickestraße 15, 21073, Hamburg, Germany
| | - Yaeseong Hong
- Institute of Bioprocess and Biosystems Engineering, Hamburg University of Technology, Denickestraße 15, 21073, Hamburg, Germany
| | - An-Ping Zeng
- Center of Synthetic Biology and Integrated Bioengineering, School of Engineering, Westlake University, Hangzhou, 310024, Zhejiang, China.
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Effects of Individual and Block Freezing on the Quality of Pacific Oyster (Crassostrea gigas) during Storage under Different Pretreatment Conditions. SUSTAINABILITY 2022. [DOI: 10.3390/su14159404] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
In this study, a series of pretreatments, including ice-glazing, polyphosphate impregnated, and both ice-glazing and polyphosphate impregnated, were employed to pretreat shucked oysters in order to explore the optimal processing conditions for long-time storage. The effect of repeated freezing-thawing cycles on the quality of oysters was evaluated. Several quality indicators were used to investigate the effects of pretreatment. For the VBN (volatile salt-based nitrogen) value, the lowest value was 9.1 ± 0.2 of BPG (block oyster with polyphosphate impregnated and ice-glazing), which was significantly lower than 9.6 ± 0.2 of IPG (individual oyster with polyphosphate impregnated and ice-glazing). In terms of drip loss, there was no significant difference between the IPG (21.0 ± 0.2%) and the BPG (20.8 ± 0.2%). In addition, the highest WHC% (water holding capacity) was IPG (65.5 ± 0.5%) which was slightly lower than BPG (67.6 ± 0.6%). As compared to the experimental control, the IPG and BPG had the best appearance and color. In terms of TAPC (total aerobic plate count), with the increase of freezing storage time, each group showed a slight downward trend, but the difference was not statistically significant. After repeated freezing-thawing of block frozen oysters, there were significant differences in drip loss, WHC, and cooked taste with the increasing number of times, and there was a trend of deterioration (p < 0.05). Repeated freezing and thawing can seriously degrade the quality of oysters, so individual freezing (especially IPG) should be the most appropriate processing method.
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Xue SJ, Zhang JR, Zhang RX, Qin Y, Yang XB, Jin GJ, Tao YS. Oxidation-reduction potential affects medium-chain fatty acid ethyl ester production during wine alcohol fermentation. Food Res Int 2022; 157:111369. [DOI: 10.1016/j.foodres.2022.111369] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2022] [Revised: 05/04/2022] [Accepted: 05/10/2022] [Indexed: 12/24/2022]
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12
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Virdis B, Hoelzle R, Marchetti A, Boto ST, Rosenbaum MA, Blasco-Gómez R, Puig S, Freguia S, Villano M. Electro-fermentation: Sustainable bioproductions steered by electricity. Biotechnol Adv 2022; 59:107950. [PMID: 35364226 DOI: 10.1016/j.biotechadv.2022.107950] [Citation(s) in RCA: 23] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2021] [Revised: 02/22/2022] [Accepted: 03/24/2022] [Indexed: 01/06/2023]
Abstract
The market of biobased products obtainable via fermentation processes is steadily increasing over the past few years, driven by the need to create a decarbonized economy. To date, industrial fermentation (IF) employs either pure or mixed microbial cultures (MMC) whereby the type of the microbial catalysts and the used feedstock affect metabolic pathways and, in turn, the type of product(s) generated. In many cases, especially when dealing with MMC, the economic viability of IF is hindered by factors such as the low attained product titer and selectivity, which ultimately challenge the downstream recovery and purification steps. In this context, electro-fermentation (EF) represents an innovative approach, based on the use of a polarized electrode interface to trigger changes in the rate, yield, titer or product distribution deriving from traditional fermentation processes. In principle, the electrode in EF can act as an electron acceptor (i.e., anodic electro-fermentation, AEF) or donor (i.e., cathodic electro-fermentation, CEF), or simply as a mean to control the oxidation-reduction potential of the fermentation broth. However, the molecular and biochemical basis underlying the EF process are still largely unknown. This review paper provides a comprehensive overview of recent literature studies including both AEF and CEF examples with either pure or mixed microbial cultures. A critical analysis of biochemical, microbiological, and engineering aspects which presently hamper the transition of the EF technology from the laboratory to the market is also presented.
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Affiliation(s)
- Bernardino Virdis
- Australian Centre for Water and Environmental Biotechnology (ACWEB, formerly AWMC), The University of Queensland, Brisbane, QLD 4072, Australia
| | - Robert Hoelzle
- School of Earth and Environmental Sciences, The University of Queensland, Brisbane, QLD 4072, Australia
| | - Angela Marchetti
- Department of Chemistry, Sapienza University of Rome, P.le Aldo Moro 5, 00185 Rome, Italy
| | - Santiago T Boto
- Bio Pilot Plant, Leibniz Institute for Natural Product Research and Infection Biology - Hans-Knöll-Institute (HKI), 07745 Jena, Germany; Faculty of Biological Sciences, Friedrich Schiller University (FSU), 07743 Jena, Germany
| | - Miriam A Rosenbaum
- Bio Pilot Plant, Leibniz Institute for Natural Product Research and Infection Biology - Hans-Knöll-Institute (HKI), 07745 Jena, Germany; Faculty of Biological Sciences, Friedrich Schiller University (FSU), 07743 Jena, Germany
| | - Ramiro Blasco-Gómez
- LEQUIA, Institute of the Environment, University of Girona, Maria Aurèlia Capmany 69, 17003 Girona, Spain
| | - Sebastià Puig
- LEQUIA, Institute of the Environment, University of Girona, Maria Aurèlia Capmany 69, 17003 Girona, Spain
| | - Stefano Freguia
- Department of Chemical Engineering, The University of Melbourne, Parkville, VIC 3010, Australia
| | - Marianna Villano
- Department of Chemistry, Sapienza University of Rome, P.le Aldo Moro 5, 00185 Rome, Italy.
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Akermann A, Weiermüller J, Chodorski JN, Nestriepke MJ, Baclig MT, Ulber R. Optimization of bioprocesses with Brewers' spent grain and Cellulomonas uda. Eng Life Sci 2022; 22:132-151. [PMID: 35382540 PMCID: PMC8961044 DOI: 10.1002/elsc.202100053] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2021] [Revised: 07/05/2021] [Accepted: 07/29/2021] [Indexed: 01/09/2023] Open
Abstract
Brewers' spent grain (BSG) is a low-value by-product of the brewing process, which is produced in large quantities every year. In this study, the lignocellulosic feedstock (solid BSG) was used to optimize fermentations with Cellulomonas uda. Under aerobic conditions, maximum cellulase activities of 0.98 nkat∙mL-1, maximum xylanase activities of 5.00 nkat∙mL-1 and cell yields of 0.22 gCells∙gBSG -1 were achieved. Under anaerobic conditions, enzyme activities and cell yields were lower, but valuable liquid products (organic acids, ethanol) were produced with a yield of 0.41 gProd∙gBSG -1. The growth phase of the organisms was monitored by measuring extracellular concentrations of two fluorophores pyridoxin (aerobic) and tryptophan (anaerobic) and by cell count. By combining reductive with anaerobic conditions, the ratio of ethanol to acetate was increased from 1.08 to 1.59 molEtOH∙molAc -1. This ratio was further improved to 9.2 molEtOH∙molAc -1 by lowering the pH from 7.4 to 5.0 without decreasing the final ethanol concentration. A fermentation in a bioreactor with 15 w% BSG instead of 5 w% BSG quadrupled the acetate concentration, whilst ethanol was removed by gas stripping. This study provides various ideas for optimizing and monitoring fermentations with solid substrates, which can support feasibility and incorporation into holistic biorefining approaches in the future.
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Affiliation(s)
- Alexander Akermann
- TU KaiserslauternDepartment of Mechanical and Process EngineeringKaiserslauternGermany
| | - Jens Weiermüller
- TU KaiserslauternDepartment of Mechanical and Process EngineeringKaiserslauternGermany
| | | | | | - Maria Teresa Baclig
- TU KaiserslauternDepartment of Mechanical and Process EngineeringKaiserslauternGermany
| | - Roland Ulber
- TU KaiserslauternDepartment of Mechanical and Process EngineeringKaiserslauternGermany
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14
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Vanyan L, Trchounian K. HyfF subunit of hydrogenase 4 is crucial for regulating F OF 1 dependent proton/potassium fluxes during fermentation of various concentrations of glucose. J Bioenerg Biomembr 2022; 54:69-79. [PMID: 35106641 DOI: 10.1007/s10863-022-09930-x] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2021] [Accepted: 01/12/2022] [Indexed: 11/26/2022]
Abstract
Escherichia coli anaerobically ferment glucose and perform proton/potassium exchange at pH 7.5. The role of hyf (hydrogenase 4) subunits (HyfBDF) in sensing different concentrations of glucose (2 g L-1 or 8 g L-1) via regulating H+/K+ exchange was studied. HyfB, HyfD and HyfF part of a protein family of NADH-ubiquinone oxidoreductase ND2, ND4 and ND5 subunits is predicted to operate as proton pump. Specific growth rate was optimal in wild type and mutants grown on 2 g L-1 glucose reaching ~ 0.8 h-1. It was shown that in wild type cells proton but not potassium fluxes were stimulated ~ 1.7 fold reaching up to 1.95 mmol/min when cells were grown in the presence of 8 g L-1 glucose. Interestingly, cells grown on peptone only had similar proton/potassium fluxes as grown on 2 g L-1glucose. H+/K+ fluxes of the cells grown on 2 g L-1 but not 8 g L-1 glucose depend on externally added glucose concentration in the assays. DCCD-sensitive H+ fluxes were tripled and K+ fluxes doubled in wild type cells grown on 8 g L-1 glucose compared to 2 g L-1 when in the assays 2 g L-1glucose was added. Interestingly, in hyfF mutant when cells were grown on 2 g L-1glucose and in 2 g L-1 assays DCCD-sensitive fluxes were not determined compared to wild type while in hyfD mutant it was doubled reaching up to 0.657 mmol/min. In hyf mutants DCCD-sensitive K+ fluxes were stimulated in hyfD and hyfF mutants compared to wild type but depend on external glucose concentration. DCCD-sensitive H+/K+ ratio was equal to ~ 2 except hyfF mutant grown and assayed on 2 g L-1glucose while in 8 g L-1 conditions role of hyfB and hyfD is considered. Taken together it can be concluded that Hyd-4 subunits (HyfBDF) play key role in sensing glucose concentration for regulation of DCCD-sensitive H+/K+ fluxes for maintaining proton motive force generation.
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Affiliation(s)
- Liana Vanyan
- Department of Biochemistry, Microbiology and Biotechnology, Scientific-Research Institute of Biology, Faculty of Biology, Yerevan State University, 1 A. Manoogian str., 0025, Yerevan, Armenia
- Microbial Biotechnologies and Biofuel Innovation Center, Yerevan State University, 1 A. Manoogian str., 0025, Yerevan, Armenia
| | - Karen Trchounian
- Department of Biochemistry, Microbiology and Biotechnology, Scientific-Research Institute of Biology, Faculty of Biology, Yerevan State University, 1 A. Manoogian str., 0025, Yerevan, Armenia.
- Microbial Biotechnologies and Biofuel Innovation Center, Yerevan State University, 1 A. Manoogian str., 0025, Yerevan, Armenia.
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15
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Gevorgyan H, Khalatyan S, Vassilian A, Trchounian K. The role of Escherichia coli FhlA transcriptional activator in generation of proton motive force and F O F 1 -ATPase activity at pH 7.5. IUBMB Life 2021; 73:883-892. [PMID: 33773019 DOI: 10.1002/iub.2470] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2021] [Revised: 03/08/2021] [Accepted: 03/19/2021] [Indexed: 12/29/2022]
Abstract
Escherichia coli is able to utilize the mixture of carbon sources and produce molecular hydrogen (H2 ) via formate hydrogen lyase (FHL) complexes. In current work role of transcriptional activator of formate regulon FhlA in generation of fermentation end products and proton motive force, N'N'-dicyclohexylcarbodiimide (DCCD)-sensitive ATPase activity at 20 and 72 hr growth during utilization of mixture of glucose, glycerol, and formate were investigated. It was shown that in fhlA mutant specific growth rate was ~1.5 fold lower compared to wt, while addition of DCCD abolished the growth in fhlA but not in wt. Formate was not utilized in fhlA mutant but wt cells simultaneously utilized formate with glucose. Glycerol utilization started earlier (from 2 hr) in fhlA than in wt. The DCCD-sensitive ATPase activity in wt cells membrane vesicles increased ~2 fold at 72 hr and was decreased 70% in fhlA. Addition of formate in the assays increased proton ATPase activity in wt and mutant strain. FhlA absence mainly affected the ΔpH but not ΔΨ component of Δp in the cells grown at 72 hr but not in 24 hr. The Δp in wt cells decreased from 24 to 72 hr of growth ~40 mV while in fhlA mutant it was stable. Taken together, it is suggested that FhlA regulates the concentration of fermentation end products and via influencing FO F1 -ATPase activity contributes to the proton motive force generation.
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Affiliation(s)
- Heghine Gevorgyan
- Department of Biochemistry, Microbiology and Biotechnology, Faculty of Biology, Yerevan State University, Yerevan, Armenia.,Faculty of Biology, Scientific-Research Institute of Biology, Yerevan State University, Yerevan, Armenia.,Microbial Biotechnologies and Biofuel Innovation Center, Yerevan State University, Yerevan, Armenia
| | - Satenik Khalatyan
- Department of Biochemistry, Microbiology and Biotechnology, Faculty of Biology, Yerevan State University, Yerevan, Armenia.,Microbial Biotechnologies and Biofuel Innovation Center, Yerevan State University, Yerevan, Armenia.,Laboratory of Neuroscience, Yerevan State Medical University, Yerevan, Armenia
| | - Anait Vassilian
- Department of Ecology and Nature Protection, Faculty of Biology, Yerevan State University, Yerevan, Armenia
| | - Karen Trchounian
- Department of Biochemistry, Microbiology and Biotechnology, Faculty of Biology, Yerevan State University, Yerevan, Armenia.,Faculty of Biology, Scientific-Research Institute of Biology, Yerevan State University, Yerevan, Armenia.,Microbial Biotechnologies and Biofuel Innovation Center, Yerevan State University, Yerevan, Armenia
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16
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Arbter P, Sabra W, Utesch T, Hong Y, Zeng A. Metabolomic and kinetic investigations on the electricity-aided production of butanol by Clostridium pasteurianum strains. Eng Life Sci 2021; 21:181-195. [PMID: 33716617 PMCID: PMC7923553 DOI: 10.1002/elsc.202000035] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2020] [Revised: 10/18/2020] [Accepted: 11/11/2020] [Indexed: 12/03/2022] Open
Abstract
In this contribution, we studied the effect of electro-fermentation on the butanol production of Clostridium pasteurianum strains by a targeted metabolomics approach. Two strains were examined: an electrocompetent wild type strain (R525) and a mutant strain (dhaB mutant) lacking formation of 1,3-propanediol (PDO). The dhaB-negative strain was able to grow on glycerol without formation of PDO, but displayed a high initial intracellular NADH/NAD ratio which was lowered subsequently by upregulation of the butanol production pathway. Both strains showed a 3-5 fold increase of the intracellular NADH/NAD ratio when exposed to cathodic current in a bioelectrochemical system (BES). This drove an activation of the butanol pathway and resulted in a higher molar butanol to PDO ratio for the R525 strain. Nonetheless, macroscopic electron balances suggest that no significant amount of electrons derived from the BES was harvested by the cells. Overall, this work points out that electro-fermentation can be used to trigger metabolic pathways and improve product formation, even when the used microbe cannot be considered electroactive. Accordingly, further studies are required to unveil the underlying (regulatory) mechanisms.
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Affiliation(s)
- Philipp Arbter
- Institute of Bioprocess and Biosystems EngineeringHamburg University of TechnologyHamburgGermany
| | - Wael Sabra
- Institute of Bioprocess and Biosystems EngineeringHamburg University of TechnologyHamburgGermany
| | - Tyll Utesch
- Institute of Bioprocess and Biosystems EngineeringHamburg University of TechnologyHamburgGermany
| | - Yaeseong Hong
- Institute of Bioprocess and Biosystems EngineeringHamburg University of TechnologyHamburgGermany
| | - An‐Ping Zeng
- Institute of Bioprocess and Biosystems EngineeringHamburg University of TechnologyHamburgGermany
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17
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Keller P, Noor E, Meyer F, Reiter MA, Anastassov S, Kiefer P, Vorholt JA. Methanol-dependent Escherichia coli strains with a complete ribulose monophosphate cycle. Nat Commun 2020; 11:5403. [PMID: 33106470 PMCID: PMC7588473 DOI: 10.1038/s41467-020-19235-5] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2020] [Accepted: 10/05/2020] [Indexed: 12/13/2022] Open
Abstract
Methanol is a biotechnologically promising substitute for food and feed substrates since it can be produced renewably from electricity, water and CO2. Although progress has been made towards establishing Escherichia coli as a platform organism for methanol conversion via the energy efficient ribulose monophosphate (RuMP) cycle, engineering strains that rely solely on methanol as a carbon source remains challenging. Here, we apply flux balance analysis to comprehensively identify methanol-dependent strains with high potential for adaptive laboratory evolution. We further investigate two out of 1200 candidate strains, one with a deletion of fructose-1,6-bisphosphatase (fbp) and another with triosephosphate isomerase (tpiA) deleted. In contrast to previous reported methanol-dependent strains, both feature a complete RuMP cycle and incorporate methanol to a high degree, with up to 31 and 99% fractional incorporation into RuMP cycle metabolites. These strains represent ideal starting points for evolution towards a fully methylotrophic lifestyle.
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Affiliation(s)
- Philipp Keller
- Institute of Microbiology, Department of Biology, ETH Zurich, 8093, Zurich, Switzerland
| | - Elad Noor
- Institute of Molecular Systems Biology, Department of Biology, ETH Zurich, 8093, Zurich, Switzerland
| | - Fabian Meyer
- Institute of Microbiology, Department of Biology, ETH Zurich, 8093, Zurich, Switzerland
| | - Michael A Reiter
- Institute of Microbiology, Department of Biology, ETH Zurich, 8093, Zurich, Switzerland
| | - Stanislav Anastassov
- Institute of Microbiology, Department of Biology, ETH Zurich, 8093, Zurich, Switzerland
| | - Patrick Kiefer
- Institute of Microbiology, Department of Biology, ETH Zurich, 8093, Zurich, Switzerland
| | - Julia A Vorholt
- Institute of Microbiology, Department of Biology, ETH Zurich, 8093, Zurich, Switzerland.
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18
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Mikoyan G, Karapetyan L, Vassilian A, Trchounian A, Trchounian K. External succinate and potassium ions influence Dcu dependent FOF1-ATPase activity and H+ flux of Escherichia coli at different pHs. J Bioenerg Biomembr 2020; 52:377-382. [DOI: 10.1007/s10863-020-09847-3] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2020] [Accepted: 07/19/2020] [Indexed: 01/12/2023]
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19
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Importance of consideration of oxidoreduction potential as a critical quality parameter in food industries. Food Res Int 2020; 132:109108. [PMID: 32331669 DOI: 10.1016/j.foodres.2020.109108] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2019] [Revised: 02/14/2020] [Accepted: 02/16/2020] [Indexed: 12/11/2022]
Abstract
There are many intrinsic and extrinsic factors affecting the nutritional, organoleptic, microbial-enzymatic and physicochemical characteristics of food products. Some of these factors are commonly considered by food processors such as the temperature, water activity, pH, dissolved oxygen and chemical composition, while others are less considered such as the oxidoreduction potential (Eh). This latter factor is an intrinsic electrochemical parameter expressing the tendency of the substance/medium to give or receive electrons. Contrary to what is expected, the important role of Eh is not limited to inorganic chemistry, metallic chemistry, natural water, and wastewater treatment fields but it also covers many domains in biology such as metabolic engineering, enzymatic functions, food safety, and biotechnology. Unfortunately, although the critical roles of Eh in several key reactions occurred in biological media such as food and biotechnological products, its application or controlling is still uncommon or mis-considered by food processors. The lack of specific studies and reviews concerning the Eh and its influences on the quality parameters of products could be a reason for this lack of interest from the side of food processors. Recent studies reported the potential application of this parameter in novel food processing techniques such as reducing atmosphere drying (RAD) of food products and reducing atmosphere packaging (RAP) of fresh food products for preserving the quality attributes and extending the shelf-life of food products. This paper aims to help the technical and operational personnel working in food industry sectors as well as the scientific community to have an updated and a comprehensible review about the Eh parameter permitting its consideration for potential applications in food industries.
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20
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Bulat T, Topcu A. The effect of oxidation-reduction potential on the characteristics of UF white cheese produced using single strains of Lactococcus lactis. Lebensm Wiss Technol 2019. [DOI: 10.1016/j.lwt.2019.04.025] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
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21
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Kim MY, Kim C, Ainala SK, Bae H, Jeon BH, Park S, Kim JR. Metabolic shift of Klebsiella pneumoniae L17 by electrode-based electron transfer using glycerol in a microbial fuel cell. Bioelectrochemistry 2019; 125:1-7. [DOI: 10.1016/j.bioelechem.2018.08.002] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2018] [Revised: 08/06/2018] [Accepted: 08/06/2018] [Indexed: 10/28/2022]
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22
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Zhang YH, Lin JY, Bai L, Huang M, Chen HQ, Yao S, Lyu SX. Antioxidant capacities of Bacillus endophyticus ST-1 and Ketogulonicigenium vulgare 25B-1 in vitamin C fermentation. BIOTECHNOL BIOTEC EQ 2018. [DOI: 10.1080/13102818.2018.1447854] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/17/2022] Open
Affiliation(s)
- Yun-he Zhang
- Laboratory of Food Microorganisms, College of Food Science, Shenyang Agricultural University, Shenyang, Liaoning, PR China
| | - Jie-ye Lin
- Department of Biochemistry and Molecular Biology, College of Bioscience and Biotechnology, Shenyang Agricultural University, Shenyang, Liaoning, PR China
| | - Ling Bai
- Department of Biochemistry and Molecular Biology, College of Bioscience and Biotechnology, Shenyang Agricultural University, Shenyang, Liaoning, PR China
| | - Mao Huang
- Department of Biochemistry and Molecular Biology, College of Bioscience and Biotechnology, Shenyang Agricultural University, Shenyang, Liaoning, PR China
| | - Hong-quan Chen
- Research and Development Department, Northeast Pharmaceutical General Factory of Vitamin C Company, Shenyang, Liaoning, PR China
| | - Shuo Yao
- Department of Biochemistry and Molecular Biology, College of Bioscience and Biotechnology, Shenyang Agricultural University, Shenyang, Liaoning, PR China
| | - Shu-xia Lyu
- Department of Biochemistry and Molecular Biology, College of Bioscience and Biotechnology, Shenyang Agricultural University, Shenyang, Liaoning, PR China
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23
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Zhou M, Yan B, Wong JWC, Zhang Y. Enhanced volatile fatty acids production from anaerobic fermentation of food waste: A mini-review focusing on acidogenic metabolic pathways. BIORESOURCE TECHNOLOGY 2018; 248:68-78. [PMID: 28693950 DOI: 10.1016/j.biortech.2017.06.121] [Citation(s) in RCA: 280] [Impact Index Per Article: 40.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/30/2017] [Revised: 06/21/2017] [Accepted: 06/22/2017] [Indexed: 05/11/2023]
Abstract
Recently, efficient disposal of food waste (FW) with potential resource recovery has attracted great attentions. Due to its easily biodegradable nature, rich nutrient availability and high moisture content, FW is regarded as favorable substrate for anaerobic digestion (AD). Both waste disposal and energy recovery can be fulfilled during AD of FW. Volatile fatty acids (VFAs) which are the products of the first-two stages of AD, are widely applied in chemical industry as platform chemicals recently. Concentration and distribution of VFAs is the result of acidogenic metabolic pathways, which can be affected by the micro-environment (e.g. pH) in the digester. Hence, the clear elucidation of the acidogenic metabolic pathways is essential for optimization of acidogenic process for efficient product recovery. This review summarizes major acidogenic metabolic pathways and regulating strategies for enhancing VFAs recovery during acidogenic fermentation of FW.
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Affiliation(s)
- Miaomiao Zhou
- Lab of Waste Valorization and Water Reuse, Qingdao Institute of Bioenergy and Bioprocess Technology, Chinese Academy of Sciences, 189 Songling Road, Laoshan District, Qingdao 266101, PR China; University of Chinese Academy of Sciences, No.19A Yuquan Road, Beijing 100049, PR China
| | - Binghua Yan
- Lab of Waste Valorization and Water Reuse, Qingdao Institute of Bioenergy and Bioprocess Technology, Chinese Academy of Sciences, 189 Songling Road, Laoshan District, Qingdao 266101, PR China.
| | - Jonathan W C Wong
- Sino-Forest Applied Research Centre for Pearl River Delta Environment, Department of Biology, Hong Kong Baptist University, PR China
| | - Yang Zhang
- Lab of Waste Valorization and Water Reuse, Qingdao Institute of Bioenergy and Bioprocess Technology, Chinese Academy of Sciences, 189 Songling Road, Laoshan District, Qingdao 266101, PR China
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24
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Cao W, Wang Y, Luo J, Yin J, Wan Y. Role of oxygen supply in α, ω-dodecanedioic acid biosynthesis from n-dodecane by Candida viswanathii ipe-1: Effect of stirring speed and aeration. Eng Life Sci 2017; 18:196-203. [PMID: 32624898 DOI: 10.1002/elsc.201700142] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2017] [Revised: 10/12/2017] [Accepted: 11/20/2017] [Indexed: 01/30/2023] Open
Abstract
α, ω-Dodecanedioic acid (DC12) usually serves as a monomer of polyamides or some special nylons. During the biosynthesis, oxygenation cascaded in conversion of hydrophobic n-dodecane to DC12, while the oxidation of n-dodecane took place in the intracellular space. Therefore, it was important to investigate the role of oxygen supply on the cell growth and DC12 biosynthesis. It was found that stirring speed and aeration influenced the dissolved oxygen (DO) concentration which in turn affected cell growth as well as DC12 biosynthesis. However, the effect of culture redox potential (Orp) level on DC12 biosynthesis was more significant than that of DO level. For DC12 biosynthesis, the first step was to form the emulsion droplets through the interaction of n-dodecane and the cell. When the stirring speed was enhanced, slits in the surface layer of the emulsion droplets would be increased. Thus, the substances transportation by water through the slits would be intensified, leading to an enhanced DC12 production. Compared with the batch culture at a lower stirring speed (400 rpm) without culture redox potential (Orp) control, the DC12 concentration was increased by 5 times up to 201.3 g/L with Orp controlled above 0 mV at a higher stirring speed (800 rpm).
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Affiliation(s)
- Weifeng Cao
- State Key Laboratory of Biochemical Engineering Institute of Process Engineering Chinese Academy of Sciences Beijing P. R. China
| | - Yujue Wang
- State Key Laboratory of Biochemical Engineering Institute of Process Engineering Chinese Academy of Sciences Beijing P. R. China.,University of the Chinese Academy of Sciences Chinese Academy of Sciences Beijing P. R. China
| | - Jianquan Luo
- State Key Laboratory of Biochemical Engineering Institute of Process Engineering Chinese Academy of Sciences Beijing P. R. China.,University of the Chinese Academy of Sciences Chinese Academy of Sciences Beijing P. R. China
| | - Junxiang Yin
- China National Center for Biotechnology Development Beijing P. R. China
| | - Yinhua Wan
- State Key Laboratory of Biochemical Engineering Institute of Process Engineering Chinese Academy of Sciences Beijing P. R. China.,University of the Chinese Academy of Sciences Chinese Academy of Sciences Beijing P. R. China
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25
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Huang T, Tan H, Lu F, Chen G, Wu Z. Changing oxidoreduction potential to improve water-soluble yellow pigment production with Monascus ruber CGMCC 10910. Microb Cell Fact 2017; 16:208. [PMID: 29162105 PMCID: PMC5697053 DOI: 10.1186/s12934-017-0828-0] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2017] [Accepted: 11/16/2017] [Indexed: 11/24/2022] Open
Abstract
Background Monascus pigments are widely used in the food and pharmaceutical industries due to their safety to human health. Our previous study found that glucose concentration induced extracellular oxidoreduction potential (ORP) changes could influence extracellular water-soluble yellow pigment production by Monascus ruber CGMCC 10910 in submerged fermentation. In this study, H2O2 and dithiothreitol (DTT) were used to change the oxidoreduction potential for investigating the effects of oxidative or reductive substances on Monascus yellow pigment production by Monascus ruber CGMCC 10910. Results The extracellular ORP could be controlled by H2O2 and DTT. Both cell growth and extracellular water-soluble yellow pigment production were enhanced under H2O2-induced oxidative (HIO) conditions and were inhibited under dithiothreitol-induced reductive conditions. By optimizing the amount of H2O2 added and the timing of the addition, the yield of extracellular water-soluble yellow pigments significantly increased and reached a maximum of 209 AU, when 10 mM H2O2 was added on the 3rd day of fermentation with M. ruber CGMCC 10910. Under HIO conditions, the ratio of NADH/NAD+ was much lower than that in the control group, and the expression levels of relative pigment biosynthesis genes were up-regulated; moreover, the activity of glucose-6-phosphate dehydrogenase (G6PDH) was increased while 6-phosphofructokinase (PFK) activity was inhibited. Conclusions Oxidative conditions induced by H2O2 increased water-soluble yellow pigment accumulation via up-regulation of the expression levels of relative genes and by increasing the precursors of pigment biosynthesis through redirection of metabolic flux. In contrast, reductive conditions induced by dithiothreitol inhibited yellow pigment accumulation. This experiment provides a potential strategy for improving the production of Monascus yellow pigments. Electronic supplementary material The online version of this article (10.1186/s12934-017-0828-0) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Tao Huang
- School of Biology and Biological Engineering, Guangdong Provincial Key Laboratory of Fermentation and Enzyme Engineering, South China University of Technology, Guangzhou, 510006, China
| | - Hailing Tan
- School of Biology and Biological Engineering, Guangdong Provincial Key Laboratory of Fermentation and Enzyme Engineering, South China University of Technology, Guangzhou, 510006, China
| | - Fangju Lu
- School of Biology and Biological Engineering, Guangdong Provincial Key Laboratory of Fermentation and Enzyme Engineering, South China University of Technology, Guangzhou, 510006, China
| | - Gong Chen
- School of Biology and Biological Engineering, Guangdong Provincial Key Laboratory of Fermentation and Enzyme Engineering, South China University of Technology, Guangzhou, 510006, China
| | - Zhenqiang Wu
- School of Biology and Biological Engineering, Guangdong Provincial Key Laboratory of Fermentation and Enzyme Engineering, South China University of Technology, Guangzhou, 510006, China.
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26
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Liu L, Xu QM, Chen T, Cheng JS, Yuan YJ. Artificial consortium that produces riboflavin regulates distribution of acetoin and 2,3-butanediol by Paenibacillus polymyxa CJX518. Eng Life Sci 2017; 17:1039-1049. [PMID: 32624854 DOI: 10.1002/elsc.201600239] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2016] [Revised: 05/23/2017] [Accepted: 05/29/2017] [Indexed: 11/09/2022] Open
Abstract
The introduction of an NADH/NAD+ regeneration system can regulate the distribution between acetoin and 2,3-butanediol. NADH regeneration can also enhance butanol production in coculture fermentation. In this work, a novel artificial consortium of Paenibacillus polymyxa CJX518 and recombinant Escherichia coli LS02T that produces riboflavin (VB2) was used to regulate the NADH/NAD+ ratio and, consequently, the distribution of acetoin and 2,3-butanediol by P. polymyxa. Compared with a pure culture of P. polymyxa, the level of acetoin was increased 76.7% in the P. polymyxa and recombinant E. coli coculture. Meanwhile, the maximum production and yield of acetoin in an artificial consortium with fed-batch fermentation were 57.2 g/L and 0.4 g/g glucose, respectively. Additionally, the VB2 production of recombinant E. coli could maintain a relatively low NADH/NAD+ ratio by changing NADH dehydrogenase activity. It was also found that 2,3-butanediol dehydrogenase activity was enhanced and improved acetoin production by the addition of exogenous VB2 or by being in the artificial consortium that produces VB2. These results illustrate that the coculture of P. polymyxa and recombinant E. coli has enormous potential to improve acetoin production. It was also a novel strategy to regulate the NADH/NAD+ ratio to improve the acetoin production of P. polymyxa.
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Affiliation(s)
- Lei Liu
- Key Laboratory of Systems Bioengineering (Ministry of Education) School of Chemical Engineering and Technology Tianjin University Tianjin People's Republic of China.,SynBio Research Platform Collaborative Innovation Centre of Chemical Science and Engineering (Tianjin) School of Chemical Engineering and Technology Tianjin University Tianjin People's Republic of China
| | - Qiu-Man Xu
- College of Life Science Tianjin Normal University Tianjin People's Republic of China
| | - Tao Chen
- Key Laboratory of Systems Bioengineering (Ministry of Education) School of Chemical Engineering and Technology Tianjin University Tianjin People's Republic of China.,SynBio Research Platform Collaborative Innovation Centre of Chemical Science and Engineering (Tianjin) School of Chemical Engineering and Technology Tianjin University Tianjin People's Republic of China
| | - Jing-Sheng Cheng
- Key Laboratory of Systems Bioengineering (Ministry of Education) School of Chemical Engineering and Technology Tianjin University Tianjin People's Republic of China.,SynBio Research Platform Collaborative Innovation Centre of Chemical Science and Engineering (Tianjin) School of Chemical Engineering and Technology Tianjin University Tianjin People's Republic of China
| | - Ying-Jin Yuan
- Key Laboratory of Systems Bioengineering (Ministry of Education) School of Chemical Engineering and Technology Tianjin University Tianjin People's Republic of China.,SynBio Research Platform Collaborative Innovation Centre of Chemical Science and Engineering (Tianjin) School of Chemical Engineering and Technology Tianjin University Tianjin People's Republic of China
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Aguirre M, Venema K. Challenges in simulating the human gut for understanding the role of the microbiota in obesity. Benef Microbes 2016; 8:31-53. [PMID: 27903093 DOI: 10.3920/bm2016.0113] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
There is an elevated incidence of cases of obesity worldwide. Therefore, the development of strategies to tackle this condition is of vital importance. This review focuses on the necessity of optimising in vitro systems to model human colonic fermentation in obese subjects. This may allow to increase the resolution and the physiological relevance of the information obtained from this type of studies when evaluating the potential role that the human gut microbiota plays in obesity. In light of the parameters that are currently used for the in vitro simulation of the human gut (which are mostly based on information derived from healthy subjects) and the possible difference with an obese condition, we propose to revise and improve specific standard operating procedures.
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Affiliation(s)
- M Aguirre
- 1 Top Institute of Food and Nutrition, P.O. Box 557, 6700 AA Wageningen, the Netherlands.,2 Department of Human Biology, Faculty of Health, Medicine and Life Sciences, School of Nutrition and Translational Research in Metabolism (NUTRIM), Maastricht University, P.O. Box 616, 6200 MD Maastricht, the Netherlands.,3 The Netherlands Organization for Applied Scientific Research (TNO), P.O. Box 360, 3700 AJ Zeist, the Netherlands
| | - K Venema
- 1 Top Institute of Food and Nutrition, P.O. Box 557, 6700 AA Wageningen, the Netherlands.,2 Department of Human Biology, Faculty of Health, Medicine and Life Sciences, School of Nutrition and Translational Research in Metabolism (NUTRIM), Maastricht University, P.O. Box 616, 6200 MD Maastricht, the Netherlands.,4 Beneficial Microbes Consultancy, Johan Karschstraat 3, 6709 TN Wageningen, the Netherlands
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Kim C, Ainala SK, Oh YK, Jeon BH, Park S, Kim JR. Metabolic flux change in Klebsiella pneumoniae L17 by anaerobic respiration in microbial fuel cell. BIOTECHNOL BIOPROC E 2016. [DOI: 10.1007/s12257-015-0777-6] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
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Honda Y, Hagiwara H, Ida S, Ishihara T. Application to Photocatalytic H2Production of a Whole-Cell Reaction by RecombinantEscherichia coliCells Expressing [FeFe]-Hydrogenase and Maturases Genes. Angew Chem Int Ed Engl 2016. [DOI: 10.1002/ange.201600177] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Affiliation(s)
- Yuki Honda
- International Institute for Carbon-Neutral Energy Research; Kyushu University; 744 Motooka, Nishi-ku Fukuoka 819-0395 Japan
- Department of Applied Chemistry; Faculty of Engineering; Kyushu University; 744 Motooka, Nishi-ku Fukuoka 819-0395 Japan
| | - Hidehisa Hagiwara
- International Institute for Carbon-Neutral Energy Research; Kyushu University; 744 Motooka, Nishi-ku Fukuoka 819-0395 Japan
- Department of Applied Chemistry; Faculty of Engineering; Kyushu University; 744 Motooka, Nishi-ku Fukuoka 819-0395 Japan
| | - Shintaro Ida
- International Institute for Carbon-Neutral Energy Research; Kyushu University; 744 Motooka, Nishi-ku Fukuoka 819-0395 Japan
- Department of Applied Chemistry; Faculty of Engineering; Kyushu University; 744 Motooka, Nishi-ku Fukuoka 819-0395 Japan
| | - Tatsumi Ishihara
- International Institute for Carbon-Neutral Energy Research; Kyushu University; 744 Motooka, Nishi-ku Fukuoka 819-0395 Japan
- Department of Applied Chemistry; Faculty of Engineering; Kyushu University; 744 Motooka, Nishi-ku Fukuoka 819-0395 Japan
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Honda Y, Hagiwara H, Ida S, Ishihara T. Application to Photocatalytic H2Production of a Whole-Cell Reaction by RecombinantEscherichia coliCells Expressing [FeFe]-Hydrogenase and Maturases Genes. Angew Chem Int Ed Engl 2016; 55:8045-8. [DOI: 10.1002/anie.201600177] [Citation(s) in RCA: 62] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2016] [Revised: 03/15/2016] [Indexed: 11/11/2022]
Affiliation(s)
- Yuki Honda
- International Institute for Carbon-Neutral Energy Research; Kyushu University; 744 Motooka, Nishi-ku Fukuoka 819-0395 Japan
- Department of Applied Chemistry; Faculty of Engineering; Kyushu University; 744 Motooka, Nishi-ku Fukuoka 819-0395 Japan
| | - Hidehisa Hagiwara
- International Institute for Carbon-Neutral Energy Research; Kyushu University; 744 Motooka, Nishi-ku Fukuoka 819-0395 Japan
- Department of Applied Chemistry; Faculty of Engineering; Kyushu University; 744 Motooka, Nishi-ku Fukuoka 819-0395 Japan
| | - Shintaro Ida
- International Institute for Carbon-Neutral Energy Research; Kyushu University; 744 Motooka, Nishi-ku Fukuoka 819-0395 Japan
- Department of Applied Chemistry; Faculty of Engineering; Kyushu University; 744 Motooka, Nishi-ku Fukuoka 819-0395 Japan
| | - Tatsumi Ishihara
- International Institute for Carbon-Neutral Energy Research; Kyushu University; 744 Motooka, Nishi-ku Fukuoka 819-0395 Japan
- Department of Applied Chemistry; Faculty of Engineering; Kyushu University; 744 Motooka, Nishi-ku Fukuoka 819-0395 Japan
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31
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Lisle JT. Natural inactivation of Escherichia coli in anaerobic and reduced groundwater. J Appl Microbiol 2016; 120:1739-50. [PMID: 26972559 DOI: 10.1111/jam.13126] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2015] [Revised: 03/03/2016] [Accepted: 03/06/2016] [Indexed: 11/28/2022]
Abstract
AIMS Inactivation rates of Escherichia coli in groundwater have most often been determined in aerobic and oxidized systems. This study examined E. coli inactivation rates in anaerobic and extremely reduced groundwater systems that have been identified as recharge zones. METHODS AND RESULTS Groundwater from six artesian wells was diverted to above-ground, flow-through mesocosms that contained laboratory grown E. coli in diffusion chambers. All groundwater was anaerobic and extremely reduced (ORP < -300 mV). Cells were plated onto mTEC agar during 21-day incubation periods. All data fit a bi-phasic inactivation model, with >95% of the E. coli population being inactivated <11·0 h (mean k = 0·488 ±0·188 h(-1) ). CONCLUSIONS The groundwater geochemical conditions enhanced the inactivation of E. coli to rates approx. 21-fold greater than previously published inactivation rate in groundwater (mean k = 0·023 ± 0·030 h(-1) ). Also, mTEC agar inhibits E. coli growth following exposure to anaerobic and reduced groundwater. SIGNIFICANCE AND IMPACT OF THE STUDY Aquifer recharge zones with geochemical characteristics observed in this study complement above-ground engineered processes (e.g. filtration, disinfection), while increasing the overall indicator micro-organism log-reduction rate of a facility.
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Affiliation(s)
- J T Lisle
- US Geological Survey, St. Petersburg Coastal & Marine Science Center, St. Petersburg, FL, USA
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Lu Y, Zhao H, Zhang C, Xing XH. Insights into the global regulation of anaerobic metabolism for improved biohydrogen production. BIORESOURCE TECHNOLOGY 2016; 200:35-41. [PMID: 26476162 DOI: 10.1016/j.biortech.2015.10.007] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/26/2015] [Revised: 10/02/2015] [Accepted: 10/06/2015] [Indexed: 06/05/2023]
Abstract
To improve the biohydrogen yield in bacterial dark fermentation, a new approach of global anaerobic regulation was introduced. Two cellular global regulators FNR and NarP were overexpressed in two model organisms: facultatively anaerobic Enterobacter aerogenes (Ea) and strictly anaerobic Clostridium paraputrificum (Cp). The overexpression of FNR and NarP greatly altered anaerobic metabolism and increased the hydrogen yield by 40%. Metabolic analysis showed that the global regulation caused more reducing environment inside the cell. To get a thorough understanding of the global metabolic regulation, more genes (fdhF, fhlA, ppk, Cb-fdh1, and Sc-fdh1) were overexpressed in different Ea and Cp mutants. For the first time, it demonstrated that there were approximately linear relationships between the relative change of hydrogen yield and the relative change of NADH yield or ATP yield. It implied that cellular reducing power and energy level played vital roles in the biohydrogen production.
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Affiliation(s)
- Yuan Lu
- Key Lab of Industrial Biocatalysis of Ministry of Education (Tsinghua University), China; Institute of Biochemical Engineering, Department of Chemical Engineering, Tsinghua University, Beijing 100084, China
| | - Hongxin Zhao
- Key Lab of Industrial Biocatalysis of Ministry of Education (Tsinghua University), China; Institute of Biochemical Engineering, Department of Chemical Engineering, Tsinghua University, Beijing 100084, China; Zhejiang Province Key Laboratory of Plant Secondary Metabolism and Regulation, College of Life Sciences, Zhejiang Sci-Tech University, Hangzhou 310018, China; College of Chemistry and Life Sciences, Shenyang Normal University, Shenyang 110034, China
| | - Chong Zhang
- Key Lab of Industrial Biocatalysis of Ministry of Education (Tsinghua University), China; Institute of Biochemical Engineering, Department of Chemical Engineering, Tsinghua University, Beijing 100084, China
| | - Xin-Hui Xing
- Key Lab of Industrial Biocatalysis of Ministry of Education (Tsinghua University), China; Institute of Biochemical Engineering, Department of Chemical Engineering, Tsinghua University, Beijing 100084, China.
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Tian X, Zhang N, Yang Y, Wang Y, Chu J, Zhuang Y, Zhang S. The effect of redox environment on l -lactic acid production by Lactobacillus paracasei —A proof by genetically encoded in vivo NADH biosensor. Process Biochem 2015. [DOI: 10.1016/j.procbio.2015.10.001] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
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Abstract
Pyruvate and acetyl-CoA form the backbone of central metabolism. The nonoxidative cleavage of pyruvate to acetyl-CoA and formate by the glycyl radical enzyme pyruvate formate lyase is one of the signature reactions of mixed-acid fermentation in enterobacteria. Under these conditions, formic acid accounts for up to one-third of the carbon derived from glucose. The further metabolism of acetyl-CoA to acetate via acetyl-phosphate catalyzed by phosphotransacetylase and acetate kinase is an exemplar of substrate-level phosphorylation. Acetyl-CoA can also be used as an acceptor of the reducing equivalents generated during glycolysis, whereby ethanol is formed by the polymeric acetaldehyde/alcohol dehydrogenase (AdhE) enzyme. The metabolism of acetyl-CoA via either the acetate or the ethanol branches is governed by the cellular demand for ATP and the necessity to reoxidize NADH. Consequently, in the absence of an electron acceptor mutants lacking either branch of acetyl-CoA metabolism fail to cleave pyruvate, despite the presence of PFL, and instead reduce it to D-lactate by the D-lactate dehydrogenase. The conversion of PFL to the active, radical-bearing species is controlled by a radical-SAM enzyme, PFL-activase. All of these reactions are regulated in response to the prevalent cellular NADH:NAD+ ratio. In contrast to Escherichia coli and Salmonella species, some genera of enterobacteria, e.g., Klebsiella and Enterobacter, produce the more neutral product 2,3-butanediol and considerable amounts of CO2 as fermentation products. In these bacteria, two molecules of pyruvate are converted to α-acetolactate (AL) by α-acetolactate synthase (ALS). AL is then decarboxylated and subsequently reduced to the product 2,3-butandiol.
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Tang B, Zhang D, Li S, Xu Z, Feng X, Xu H. Enhanced poly(γ-glutamic acid) production by H 2 O 2 -induced reactive oxygen species in the fermentation of Bacillus subtilis NX-2. Biotechnol Appl Biochem 2015. [PMID: 26202728 DOI: 10.1002/bab.1416] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
Effects of reactive oxygen species (ROS) on cell growth and poly(γ-glutamic acid) (γ-PGA) synthesis were studied by adding hydrogen peroxide to a medium of Bacillus subtilis NX-2. After optimizing the addition concentration and time of H2 O2 , a maximum concentration of 33.9 g/L γ-PGA was obtained by adding 100 µM H2 O2 to the medium after 24 H. This concentration was 20.6% higher than that of the control. The addition of diphenyleneiodonium chloride (ROS inhibitor) can interdict the effect of H2 O2 -induced ROS. Transcriptional levels of the cofactors and relevant genes were also determined under ROS stress to illustrate the possible metabolic mechanism contributing to the improve γ-PGA production. The transcriptional levels of genes belonging to the tricarboxylic acid cycle and electron transfer chain system were significantly increased by ROS, which decreased the NADH/NAD+ ratio and increased the ATP levels, thereby providing more reducing power and energy for γ-PGA biosynthesis. The enhanced γ-PGA synthetic genes also directly promoted the formation of γ-PGA. This study was the first to use the ROS control strategy for γ-PGA fermentation and provided valuable information on the possible mechanism by which ROS regulated γ-PGA biosynthesis in B. subtilis NX-2.
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Affiliation(s)
- Bao Tang
- State Key Laboratory of Materials-Oriented Chemical Engineering, Nanjing, People's Republic of China
- College of Food Science and Light Industry, Nanjing Tech University, Nanjing, People's Republic of China
| | - Dan Zhang
- State Key Laboratory of Materials-Oriented Chemical Engineering, Nanjing, People's Republic of China
- College of Food Science and Light Industry, Nanjing Tech University, Nanjing, People's Republic of China
| | - Sha Li
- State Key Laboratory of Materials-Oriented Chemical Engineering, Nanjing, People's Republic of China
- College of Food Science and Light Industry, Nanjing Tech University, Nanjing, People's Republic of China
| | - Zongqi Xu
- State Key Laboratory of Materials-Oriented Chemical Engineering, Nanjing, People's Republic of China
- College of Food Science and Light Industry, Nanjing Tech University, Nanjing, People's Republic of China
| | - Xiaohai Feng
- State Key Laboratory of Materials-Oriented Chemical Engineering, Nanjing, People's Republic of China.
- College of Food Science and Light Industry, Nanjing Tech University, Nanjing, People's Republic of China.
| | - Hong Xu
- State Key Laboratory of Materials-Oriented Chemical Engineering, Nanjing, People's Republic of China.
- College of Food Science and Light Industry, Nanjing Tech University, Nanjing, People's Republic of China.
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Zhuge X, Li J, Shin HD, Liu L, Du G, Chen J. Improved propionic acid production with metabolically engineered Propionibacterium jensenii by an oxidoreduction potential-shift control strategy. BIORESOURCE TECHNOLOGY 2015; 175:606-612. [PMID: 25453933 DOI: 10.1016/j.biortech.2014.10.038] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/31/2014] [Revised: 10/08/2014] [Accepted: 10/09/2014] [Indexed: 06/04/2023]
Abstract
In this study, a three-stage oxidoreduction potential (ORP) control strategy was developed to improve propionic acid (PA) production using engineered Propionibacterium jensenii ATCC 4868 (pZGX04-gldA) in a 3-L bioreactor. Specifically, ORP was controlled at -200mV from 0 to 36h, -300mV from 36 to 156h, and -400mV after 156h. The PA titer increased from 21.38 to 27.31g/L. The effects of ORP regulation on key intracellular metabolites were studied, demonstrating that ORP can both regulate NADH/NAD(+) ratio and the activities of some enzymes involved in electron transport and redistribute metabolic flux. We integrated the ORP control strategy with a fed-batch culture method and increased PA production to 39.53g/L. This new ORP control strategy may be useful in the optimization of other anaerobic processes.
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Affiliation(s)
- Xin Zhuge
- Key Laboratory of Carbohydrate Chemistry and Biotechnology, Ministry of Education, Jiangnan University, Wuxi 214122, China; Key Laboratory of Industrial Biotechnology, Ministry of Education, Jiangnan University, Wuxi 214122, China; Synergetic Innovation Center of Food Safety and Nutrition, Wuxi 214122, China
| | - Jianghua Li
- Key Laboratory of Carbohydrate Chemistry and Biotechnology, Ministry of Education, Jiangnan University, Wuxi 214122, China; Key Laboratory of Industrial Biotechnology, Ministry of Education, Jiangnan University, Wuxi 214122, China; Synergetic Innovation Center of Food Safety and Nutrition, Wuxi 214122, China
| | - Hyun-Dong Shin
- School of Chemical and Biomolecular Engineering, Georgia Institute of Technology, Atlanta 30332, USA
| | - Long Liu
- Key Laboratory of Carbohydrate Chemistry and Biotechnology, Ministry of Education, Jiangnan University, Wuxi 214122, China; Key Laboratory of Industrial Biotechnology, Ministry of Education, Jiangnan University, Wuxi 214122, China; Synergetic Innovation Center of Food Safety and Nutrition, Wuxi 214122, China.
| | - Guocheng Du
- Key Laboratory of Carbohydrate Chemistry and Biotechnology, Ministry of Education, Jiangnan University, Wuxi 214122, China; Key Laboratory of Industrial Biotechnology, Ministry of Education, Jiangnan University, Wuxi 214122, China; Synergetic Innovation Center of Food Safety and Nutrition, Wuxi 214122, China.
| | - Jian Chen
- Synergetic Innovation Center of Food Safety and Nutrition, Wuxi 214122, China; National Engineering of Laboratory for Cereal Fermentation Technology, Jiangnan University, Wuxi 214122, China
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Dai JJ, Cheng JS, Liang YQ, Jiang T, Yuan YJ. Regulation of extracellular oxidoreduction potential enhanced (R,R)-2,3-butanediol production by Paenibacillus polymyxa CJX518. BIORESOURCE TECHNOLOGY 2014; 167:433-40. [PMID: 25006018 DOI: 10.1016/j.biortech.2014.06.044] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/25/2014] [Revised: 06/11/2014] [Accepted: 06/12/2014] [Indexed: 05/23/2023]
Abstract
Cellular redox status and oxygen availability influence the product formation. Herein, decreasing agitation speed or adding vitamin C (Vc) achieved the 2,3-BDL yield of 0.40 g g(-1) or 0.39 g g(-1)glucose under batch fermentation, respectively. To our knowledge, this is the highest 2,3-BDL yield reported so far for Paenibacillus polymyxa without adding acetic acid. The NADH/NAD(+) ratio and 2,3-BDL titer could be increased significantly by reducing the agitation speed or adding Vc, indicating that the enhancement of 2,3-BDL is closely associated with the adjustment of NADH/NAD(+) ratio. Especially, Vc addition elevated the 2,3-BDL titer from 43.66 g L(-1) to 71.71 g L(-1) within 54 h under fed-batch fermentation. This is the highest titer of 2,3-BDL so far reported for P. polymyxa from glucose fermentation. This work provides a new strategy to improve 2,3-BDL production and helps us to understand the responses of P. polymyxa to extracellular oxidoreduction potential.
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Affiliation(s)
- Jun-Jun Dai
- Key Laboratory of Systems Bioengineering, Ministry of Education (Tianjin University), Tianjin 300072, People's Republic of China; School of Chemical Engineering and Technology, Tianjin University, Tianjin 300072, People's Republic of China; Collaborative Innovation Center of Chemical Science and Engineering (Tianjin), Tianjin 300072, People's Republic of China
| | - Jing-Sheng Cheng
- Key Laboratory of Systems Bioengineering, Ministry of Education (Tianjin University), Tianjin 300072, People's Republic of China; School of Chemical Engineering and Technology, Tianjin University, Tianjin 300072, People's Republic of China; Collaborative Innovation Center of Chemical Science and Engineering (Tianjin), Tianjin 300072, People's Republic of China.
| | - Ying-Quan Liang
- Key Laboratory of Systems Bioengineering, Ministry of Education (Tianjin University), Tianjin 300072, People's Republic of China; School of Chemical Engineering and Technology, Tianjin University, Tianjin 300072, People's Republic of China
| | - Tong Jiang
- School of Chemical Engineering and Technology, Tianjin University, Tianjin 300072, People's Republic of China; Collaborative Innovation Center of Chemical Science and Engineering (Tianjin), Tianjin 300072, People's Republic of China
| | - Ying-Jin Yuan
- Key Laboratory of Systems Bioengineering, Ministry of Education (Tianjin University), Tianjin 300072, People's Republic of China; School of Chemical Engineering and Technology, Tianjin University, Tianjin 300072, People's Republic of China; Collaborative Innovation Center of Chemical Science and Engineering (Tianjin), Tianjin 300072, People's Republic of China
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Zhang X, Xue C, Zhao F, Li D, Yin J, Zhang C, Caiyin Q, Lu W. Suitable extracellular oxidoreduction potential inhibit rex regulation and effect central carbon and energy metabolism in Saccharopolyspora spinosa. Microb Cell Fact 2014; 13:98. [PMID: 25158803 PMCID: PMC4172946 DOI: 10.1186/s12934-014-0098-z] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2014] [Accepted: 06/26/2014] [Indexed: 11/10/2022] Open
Abstract
Background Polyketides, such as spinosad, are mainly synthesized in the stationary phase of the fermentation. The synthesis of these compounds requires many primary metabolites, such as acetyl-CoA, propinyl-CoA, NADPH, and succinyl-CoA. Their synthesis is also significantly influenced by NADH/NAD+. Rex is the sensor of NADH/NAD+ redox state, whose structure is under the control of NADH/NAD+ ratio. The structure of rex controls the expression of many NADH dehydrogenases genes and cytochrome bd genes. Intracellular redox state can be influenced by adding extracellular electron acceptor H2O2. The effect of extracellular oxidoreduction potential on spinosad production has not been studied. Although extracellular oxidoreduction potential is an important environment effect in polyketides production, it has always been overlooked. Thus, it is important to study the effect of extracellular oxidoreduction potential on Saccharopolyspora spinosa growth and spinosad production. Results During stationary phase, S. spinosa was cultured under oxidative (H2O2) and reductive (dithiothreitol) conditions. The results show that the yield of spinosad and pseudoaglycone increased 3.11 fold under oxidative condition. As H2O2 can be served as extracellular electron acceptor, the ratios of NADH/NAD+ were measured. We found that the ratio of NADH/NAD+ under oxidative condition was much lower than that in the control group. The expression of cytA and cytB in the rex mutant indicated that the expression of these two genes was controlled by rex, and it was not activated under oxidative condition. Enzyme activities of PFK, ICDH, and G6PDH and metabolites results indicated that more metabolic flux flow through spinosad synthesis. Conclusion The regulation function of rex was inhibited by adding extracellular electron acceptor-H2O2 in the stationary phase. Under this condition, many NADH dehydrogenases which were used to balance NADH/NAD+ by converting useful metabolites to useless metabolites and unefficient terminal oxidases (cytochrome bd) were not expressed. So lots of metabolites were not waste to balance. As a result, un-wasted metabolites related to spinosad and PSA synthesis resulted in a high production of spinosad and PSA under oxidative condition. Electronic supplementary material The online version of this article (doi:10.1186/s12934-014-0098-z) contains supplementary material, which is available to authorized users.
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Jeon B, Yi J, Park D. Effects of H2 and electrochemical reducing power on metabolite production by Clostridium acetobutylicum KCTC1037. Biosci Biotechnol Biochem 2014; 78:503-9. [PMID: 25036842 DOI: 10.1080/09168451.2014.882743] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
Abstract
A conventional fermenter (CF), a single-cathode fermenter (SCF), and a double-cathode fermenter (DCF) were employed to evaluate and compare the effects of H2 and electrochemical reducing power on metabolite production by Clostridium acetobutylicum KCTC1037. The source of the external reducing power for CF was H2, for the SCF was electrochemically reduced neutral red-modified graphite felt electrode (NR-GF), and for the DCF was electrochemically reduced combination of NR-GF and platinum plate electrodes (NR-GF/PtP). The metabolites produced from glucose or CO2 by strain KCTC1037 cultivated in the DCF were butyrate, ethanol, and butanol, but ethanol and butanol were not produced from glucose or CO2 by strain KCTC1037 cultivated in the CF and SCF. It is possible that electrochemically reduced NR-GF/PtP is a more effective source of internal and external reducing power than H2 or NR-GF for strain KCTC1037 to produce metabolites from glucose and CO2. This research might prove useful in developing fermentation technology to actualize direct bioalcohol production of fermentation bacteria from CO2.
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Affiliation(s)
- Boyoung Jeon
- a Department of Chemical and Biological Engineering , Seokyeong University , Seoul , Korea
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40
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Engineering redox balance through cofactor systems. Trends Biotechnol 2014; 32:337-43. [DOI: 10.1016/j.tibtech.2014.04.003] [Citation(s) in RCA: 117] [Impact Index Per Article: 10.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2013] [Revised: 03/26/2014] [Accepted: 04/02/2014] [Indexed: 12/12/2022]
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Metabolic changes in Klebsiella oxytoca in response to low oxidoreduction potential, as revealed by comparative proteomic profiling integrated with flux balance analysis. Appl Environ Microbiol 2014; 80:2833-41. [PMID: 24584239 DOI: 10.1128/aem.03327-13] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Oxidoreduction potential (ORP) is an important physiological parameter for biochemical production in anaerobic or microaerobic processes. However, the effect of ORP on cellular physiology remains largely unknown, which hampers the design of engineering strategies targeting proteins associated with ORP response. Here we characterized the effect of altering ORP in a 1,3-propanediol producer, Klebsiella oxytoca, by comparative proteomic profiling combined with flux balance analysis. Decreasing the extracellular ORP from -150 to -240 mV retarded cell growth and enhanced 1,3-propanediol production. Comparative proteomic analysis identified 61 differentially expressed proteins, mainly involved in carbohydrate catabolism, cellular constituent biosynthesis, and reductive stress response. A hypothetical oxidoreductase (HOR) that catalyzes 1,3-propanediol production was markedly upregulated, while proteins involved in biomass precursor synthesis were downregulated. As revealed by subsequent flux balance analysis, low ORP induced a metabolic shift from glycerol oxidation to reduction and rebalancing of redox and energy metabolism. From the integrated protein expression profiles and flux distributions, we can construct a rational analytic framework that elucidates how (facultative) anaerobes respond to extracellular ORP changes.
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Trchounian A, Gary Sawers R. Novel insights into the bioenergetics of mixed-acid fermentation: Can hydrogen and proton cycles combine to help maintain a proton motive force? IUBMB Life 2013; 66:1-7. [DOI: 10.1002/iub.1236] [Citation(s) in RCA: 50] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2013] [Revised: 12/04/2013] [Accepted: 12/08/2013] [Indexed: 11/08/2022]
Affiliation(s)
- Armen Trchounian
- Department of Microbiology; Plants and Microbes Biotechnology, Faculty of Biology, Yerevan State University; Yerevan Armenia
| | - R. Gary Sawers
- Institute of Biology/Microbiology; Martin Luther University of Halle-Wittenberg; Halle (Saale) Germany
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Capuani A, Werner S, Behr J, Vogel RF. Effect of controlled extracellular oxidation–reduction potential on microbial metabolism and proteolysis in buckwheat sourdough. Eur Food Res Technol 2013. [DOI: 10.1007/s00217-013-2120-9] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
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Trchounian A. Mechanisms for hydrogen production by different bacteria during mixed-acid and photo-fermentation and perspectives of hydrogen production biotechnology. Crit Rev Biotechnol 2013; 35:103-13. [DOI: 10.3109/07388551.2013.809047] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
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Liu CG, Lin YH, Bai FW. Global gene expression analysis ofSaccharomyces cerevisiaegrown under redox potential-controlled very-high-gravity conditions. Biotechnol J 2013; 8:1332-40. [DOI: 10.1002/biot.201300127] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2013] [Revised: 04/09/2013] [Accepted: 04/25/2013] [Indexed: 11/08/2022]
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Ma J, Gou D, Liang L, Liu R, Chen X, Zhang C, Zhang J, Chen K, Jiang M. Enhancement of succinate production by metabolically engineered Escherichia coli with co-expression of nicotinic acid phosphoribosyltransferase and pyruvate carboxylase. Appl Microbiol Biotechnol 2013; 97:6739-47. [PMID: 23740313 DOI: 10.1007/s00253-013-4910-1] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2013] [Revised: 03/25/2013] [Accepted: 04/07/2013] [Indexed: 11/24/2022]
Abstract
Escherichia coli BA002, in which the ldhA and pflB genes are deleted, cannot utilize glucose anaerobically due to the inability to regenerate NAD(+). To restore glucose utilization, overexpression of nicotinic acid phosphoribosyltransferase (NAPRTase) encoded by the pncB gene, a rate-limiting enzyme of NAD(H) synthesis pathway, resulted in a significant increase in cell mass and succinate production under anaerobic conditions. However, a high concentration of pyruvate accumulated. Thus, co-expression of NAPRTase and the heterologous pyruvate carboxylase (PYC) of Lactococcus lactis subsp. cremoris NZ9000 in recombinant E. coli BA016 was investigated. The total concentration of NAD(H) was 9.8-fold higher in BA016 than in BA002, and the NADH/NAD(+) ratio decreased from 0.60 to 0.04. Under anaerobic conditions, BA016 consumed 17.50 g l(-1) glucose and produced 14.08 g l(-1) succinate with a small quantity of pyruvate. Furthermore, when the reducing agent dithiothreitol or reduced carbon source sorbitol was added, the cell growth and carbon source consumption rate of BA016 was reasonably enhanced and succinate productivity increased.
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Affiliation(s)
- Jiangfeng Ma
- State Key Laboratory of Materials-Oriented Chemical Engineering, College of Biotechnology and Pharmaceutical Engineering, Nanjing University of Technology, Nanjing, 211816, Jiangsu, China
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Iverson A, Garza E, Zhao J, Wang Y, Zhao X, Wang J, Manow R, Zhou S. Increasing reducing power output (NADH) of glucose catabolism for reduction of xylose to xylitol by genetically engineered Escherichia coli AI05. World J Microbiol Biotechnol 2013; 29:1225-32. [PMID: 23435875 DOI: 10.1007/s11274-013-1285-5] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2012] [Accepted: 02/07/2013] [Indexed: 10/27/2022]
Abstract
Anaerobic homofermentative production of reduced products requires additional reducing power (NADH and/or NADPH) output from glucose catabolism. Previously, with an anaerobically expressed pyruvate dehydrogenase operon (aceEF-lpd), we doubled the reducing power output to four NADH per glucose (or 1.2 xylose) catabolized anaerobically, which satisfied the NADH requirement to establish a non-transgenic homoethanol pathway (1 glucose or 1.2 xylose --> 2 acetyl-CoA + 4 NADH --> 2 ethanol) in the engineered strain, Escherichia coli SZ420 (∆frdBC ∆ldhA ∆ackA ∆focA-pflB ∆pdhR::pflBp6-pflBrbs-aceEF-lpd). In this study, E. coli SZ420 was further engineered for reduction of xylose to xylitol by (1) deleting the alcohol dehydrogenase gene (adhE) to divert NADH from the ethanol pathway; (2) deleting the glucose-specific PTS permease gene (ptsG) to eliminate catabolite repression and allow simultaneous uptake of glucose and xylose; (3) cloning the aldose reductase gene (xylI) of Candida boidinii to reduce xylose to xylitol. The resulting strain, E. coli AI05 (pAGI02), could in theory simultaneously uptake glucose and xylose, and utilize glucose as a source of reducing power for the reduction of xylose to xylitol, with an expected yield of four xylitol for each glucose consumed (YRPG = 4) under anaerobic conditions. In resting cell fermentation tests using glucose and xylose mixtures, E. coli AI05 (pAGI02) achieved an actual YRPG value of ~3.6, with xylitol as the major fermentation product and acetate as the by-product.
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Affiliation(s)
- Andrew Iverson
- Key Laboratory of Fermentation Engineering, Hubei Provincial Cooperative Innovation Center of Industrial Fermentation, College of Bioengineering, Hubei University of Technology, Wuhan, 430068, People's Republic of China
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Ignatova M, Guével B, Com E, Haddad N, Rossero A, Bogard P, Prévost H, Guillou S. Two-dimensional fluorescence difference gel electrophoresis analysis of Listeria monocytogenes submitted to a redox shock. J Proteomics 2013. [DOI: 10.1016/j.jprot.2012.11.010] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
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Kang A, Tan MH, Ling H, Chang MW. Systems-level characterization and engineering of oxidative stress tolerance in Escherichia coli under anaerobic conditions. MOLECULAR BIOSYSTEMS 2012; 9:285-95. [PMID: 23224080 DOI: 10.1039/c2mb25259g] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Despite many prior studies on microbial response to oxidative stress, our understanding of microbial tolerance against oxidative stress is currently limited to aerobic conditions, and few engineering strategies have been devised to resolve toxicity issues of oxidative stress under anaerobic conditions. Since biological processes, such as anaerobic fermentation, are frequently hampered by toxicity arising from oxidative stress, increased microbial tolerance against oxidative stress improves the overall productivity and yield of biological processes. Here, we show a systems-level analysis of oxidative stress response of Escherichia coli under anaerobic conditions, and present an engineering strategy to improve oxidative stress tolerance. First, we identified essential cellular mechanisms and regulatory factors underlying oxidative stress response under anaerobic conditions using a transcriptome analysis. In particular, we showed that nitrogen metabolisms and respiratory pathways were differentially regulated in response to oxidative stress under anaerobic and aerobic conditions. Further, we demonstrated that among transcription factors with oxidative stress-derived perturbed activity, the deletion of arcA and arcB significantly improved oxidative stress tolerance under aerobic and anaerobic conditions, respectively, whereas fnr was identified as an essential transcription factor for oxidative stress tolerance under anaerobic conditions. Moreover, we showed that oxidative stress increased the intracellular NADH : NAD(+) ratio under aerobic and anaerobic conditions, which indicates a regulatory role of NADH in oxidative stress tolerance. Based on this finding, we demonstrated that increased NADH availability through fdh1 overexpression significantly improved oxidative stress tolerance under aerobic conditions. Our results here provide novel insight into better understanding of cellular mechanisms underlying oxidative stress tolerance under anaerobic conditions, and into developing strain engineering strategies to enhance microbial tolerance against oxidative stress towards improved biological processes.
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Affiliation(s)
- Aram Kang
- Division of Chemical and Biomolecular Engineering, School of Chemical and Biomedical Engineering, Nanyang Technological University, 62 Nanyang Drive, Singapore 637459, Singapore
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Zhang D, Feng X, Li S, Chen F, Xu H. Effects of oxygen vectors on the synthesis and molecular weight of poly(γ-glutamic acid) and the metabolic characterization of Bacillus subtilis NX-2. Process Biochem 2012. [DOI: 10.1016/j.procbio.2012.07.029] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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